WASHINGTON — Osama bin Laden’s death in a ripped-from-a-spy-thriller helicopter raid and firefight gives a storied unit of U.S. special operations forces bragging rights for what has become the most famous covert operation since the Sept. 11 attacks launched on bin Laden’s orders.

The unit, called Navy SEAL Team Six, probably won’t claim the credit publicly, however.

U.S. officials, speaking on condition of anonymity, say units from SEAL Team Six dropped into bin Laden’s high-walled compound in Pakistan early Monday, sliding down ropes in the pre-dawn dark. The military won’t confirm which unit carried out the attack.

But the head of the Navy SEALs, Rear Adm. Edward Winters, sent an email congratulating his forces and warning them to keep their mouths shut.

“Be extremely careful about operational security,” he added. “The fight is not over.”

Made up of only a few hundred forces based in Dam Neck, Va., the elite SEAL unit officially known as Naval Special Warfare Development Group, or “DEVGRU,” is part of a special operations brotherhood that calls itself “the quiet professionals.”

SEAL Team Six raided targets outside war zones like Yemen and Somalia in the past three years, though the unit operates primarily in Afghanistan. The Associated Press will not publish the names of the commanding officers, to protect them and their families from possible retaliation by militants for the bin Laden operation.

The unit is overseen by the Joint Special Operations Command, which oversees the Army’s Delta Force and other special units. JSOC’s combined forces have been responsible for a quadrupling of counterterrorism raids that have targeted militants in record numbers over the past year in Afghanistan. Some 4,500 elite special operations forces and support units have been part of the surge of U.S. forces there.

CIA Director Leon Panetta was in charge of the military team during the covert operation, a U.S. official said. While the president can empower the SEALs and other counterterrorism units to carry out covert actions without CIA oversight, President Obama’s team put the intelligence agency in charge, with other elements of the national security apparatus answering to them for this mission.

SEAL Team Six actually works so often with the intelligence agency that it’s sometimes called the CIA’s Pretorian Guard – a partnership that started in Iraq, as an outgrowth of the fusion of special operations forces and intelligence in the hunt for militants there.

SEALs and Delta both, commanded by then-JSOC chief Gen. StanleyMcChrystal, learned to work much like FBI agents, first attacking a target, killing or capturing the suspects, and then gathering evidence at the scene.

McChrystal described it as building a network to chase a network, where the special operations forces work with intelligence analysts back at a joint base. The raiders, he said, could collect valuable “pocket litter” from the scene, like documents or computers, to exploit to hunt the next target.

The battlegrounds of Iraq and Afghanistan had been informally divided, with the SEALs running Afghanistan and the Army’s Delta Force conducting the bulk of the operations in Iraq, though there was overlap of each organization. There is considerable professional rivalry between them.

Delta Force units caught Saddam Hussein late in 2003, and had killed his sons Uday and Qusay in a shootout in Mosul earlier that year. The race to be the unit that captured bin Laden had been on ever since.

“Officially, Team Six doesn’t exist,” says former Navy SEAL Craig Sawyer, 47, who advises Hollywood and acts in movies about the military.

After undergoing a six-month process in which commanders scrutinized his every move, Sawyer says he was selected in the 1990s to join the team.

“It was like being recruited to an all-star team,” he said, with members often gone 300 days a year, lasting only about three years on the team before burning out.

“They train around the clock,” he said. “They know that failure will not be an option. Either they succeed or they don’t come home.”

Other special operations units joke that “SEAL” stands for “Sleep, eat, lift,” though the term actually stands for Sea, Air, Land.

“The SEALs will be the first to remind everyone that the ‘L’ in SEAL stands for land,” says retired Army Gen. Doug Brown, former commander of U.S. Special Operations Command in Tampa, Fla. “They have skills on the land equal to their skills at sea.”

Brown, who led the command from 2003 to 2007, said the operation against bin Laden is the most significant mission conducted by U.S. commando forces since the organization was formed in 1987 in the wake of the failed attempt in 1980 to rescue the American hostages in Iran.

“I can’t think of a mission as nationally important,” Brown said.

The last time the public was made aware of a SEAL raid on Pakistani soil was 2008, when the raiders flew only a mile over the border to the town of Angurada, according to Pakistani officials, speaking on condition of anonymity to discuss sensitive strategic matters. The high-value targets the Americans had been told were there had fled, and those left behind in the compound fought back, resulting in a number of civilian casualties, U.S. and Pakistani officials say, speaking on condition of anonymity to discuss a classified operation.

While the U.S. usually does not comment on covert actions, especially ones that go wrong, the 2008 incident was caught on cellphone video, so they confirmed it and apologized publicly, U.S. officials said.

The successful bin Laden mission is a much-needed boost for the unit.

The SEALs’ reputation took a hit within the special operations community after a 2010 rescue mission led to the accidental killing of British hostage Linda Norgrove, held by militants in Afghanistan. One of the

SEALs threw a fragmentation grenade at a militant when the team stormed their hideout, not realizing Norgrove was curled on the ground next to the militant.

The SEALs originally reported that Norgrove had been killed by a fighter’s suicide vest, but when the SEAL commanding officer reviewed the tape from simultaneous surveillance video, he saw an explosion after one of the SEALs threw something in Norgrove’s direction, U.S. officials say, speaking on condition of anonymity to discuss a classified operation.

One SEAL was dismissed from the unit, after he lied to a commanding officer about bringing that type of grenade on a rescue mission, when the standard practice in hostage rescue scenarios is to bring “flash-bangs,” which produce noise and light but do not kill.

DEVGRU is the same unit that rescued an American ship captain, Richard

Phillips, held hostage on a lifeboat by Somali pirates after his capture from the USS Maersk Alabama in 2009. A DEVGRU unit fired precision shots from the rocking stern of a Naval ship, killing all three pirates.